Improvement in steam-engines



PATENT QEEICE STEPHEN F. DAVENPORT, OF HALLOWELL, MAINE.v

IMPROVEMENT IN STEAMENGINES.

Specification forming part of Letters Patent No. 60,861, dated January 1, 1867.

To all whom it may concern:

Be it known that I, STEPHEN F. DAVEN- PORT, of Hallowell, in the county of Kennebec and State of Maine, have invented an Improved Steam-Engine 5 and Ido hereby declare the same to be fully described in the following specification and represented in the accompanying drawings, ot' which- Figure 1 is a top view, Fig. 2 is a horizontal section, and Fig. 3 a transverse section, of an engine of my improved construction. Fig. 4 is a side view, and Fig. 5 a top view, of its main cylinder-piston, which of itself is a cylinder provided with what I term an auxiliary piston.

The engine is designed to operate by using the steam expansively in a peculiar manner.

The main cylinder of the engine is shown at A as provided with a piston, whose head B is a hollow cylinder, closed at each end. The bearing-flanges of the head B are to be provided with a suitable packing, the drawings representing two steel expansive packing-rings, b b, as applied to each flange, and ina groove circumscribing it, each of the `said flanges having a diameter equal, or about equal, to that of the bore of the cylinder A. The piston-rod to the head B is shown at b as going through a stuiiing-box, d, at one A head of the cylinder A. Within the bore ot' the head B is the auxiliary piston C, which, while the engine is in operation, is to be perfectly stationary, its rod e being tubular, and fastened, at or near its other end, to some standard or other proper object. The steam for the supply of the engine is to enter and pass through the rod e, which is to be connected with the steam-generator by means of a pipe or suitable conduit. The head ofthe auxiliary piston C is hollow, and there is a port or opening leading out of each end of it, as shown at f and g. These ports are provided with a rocker-valve, 7L', furnished with an operative rod, t', to extend through and beyond the piston-rod 6. The head ofthe piston C is to fit the bore of the hollow piston-head B, and is to be provided with a suitable packing-such, for instance, as two or more metallic rings, h h. There is a port or'steam-passage, k, leading laterally out ot' the bore of the piston-head B, close to each end of such bore, and to one of two rotary valves, lm.

Another such port or passage, a, leads from each'ot' the valves through thev next adjacent cap or end plate o ofthe part B. Each of the valves Z m is made so that when a passage, p, of it is in one position, it will open communication between its two passages 7c and a, and when revolved-into another position the valve will close the passage k, and open communication between the passage n and the annular space r, surrounding the head B, and between its anges. The two valves lm have arms s s extending from them, and connected by a rod, t, jointed to both arms. A shaft, a, carrying a bent arm, c, on its inner end, is arranged within an exhaust-passage, w, leading out of the middle of the cylinder A. The shaft a turns in stufting-box y, iixed in the projection x, containing such passage. The steam exhausts laterally out of the passage w by a passage, z. The purpose of the shaft and its bent arm is to trip each ot' the valves l m at the proper times, which it is to be caused to do by proper mechanism applied to it, and operated by the engine. So to the valve-rod ot' the auxiliary piston a proper mechanism for actuating it or moving it lengthwise back and forth at suitable times is to be applied.

The engine thus constructed will operate as follows: Steam being admitted through the piston G into the cylinder or head B, and in one side of the head of such piston, will cause the said head B to be moved in one direction throughout the cylinder A. On the head B having arrived at the terminus of such movement, the valves are to be tripped, so as to open communication between the space which receives such steam and that part of the cylinder A which is next adjacent to that head ofthe said cylinder toward which the pistonhead B had been advanced.l At the same time the valve in the piston C is to be tripped, so as not only to cut off the entrance of steam into the space which first received it, but to open communication for the steam to operate from the reverse side of the head of the piston C. The head B will next be moved in the opposite direction, and not only by the action ofthe second quantity of steam let into it, but by the pressure of the irst amount of steam acting expansively.

The first quantity of steam, on escaping from the head B into the cylinder A, will expand C, the excess of'pressure operating to aid in moving the head B in the direction the reverse to that in which it was iirst impelled.

Dnrin g the next movement of the head B the expanded steam Will be driven into the annular space about the head B, and from thence will pass out of the exhaust-passage. Thus, during each movement of the head B in the cylinder A, the steam operating to cause such will be, assisted by the steam previously employed to effect the necessary movement ofthe head in the opposite direction, the expanded steam which operated in effecting the latter movement being expelled from the cylinder.

The engine may be made so as to cause the piston-head B to operate or be moved in one direction by the unexpanded steam, and next moved in the other direction by such steam, when allowed to expand, such being What I term a single-acting expansion-en gine; but by letti ng the steam successively on opposite sides of the head of the piston C, and into the head B, we have a double-acting engine in which the piston-head B Will be driven in either direction by the conjoint action of the unexpanded and the expanded steam.

I do not claim the combination of an expansion-cylinder and separate piston with the main cylinder and piston of an engine, the saine being so as to cause the steam, after havin g moved one piston in one direction, to expand in both cylinders, and by such expansion operate to move the other piston in its cylinder..

Vhat I claim as my invention is- My improved steam-engine, made substantially as described-viz., ot the cylinder A, the

internal piston-cylinder B, the piston C, and

their steam-passages, ports, and valves, arranged in manner as represented, and so as to operate as described, in order to cause the piston-head B to be moved by the unexpanded and expanded steam, substantially as explained.

STEPHEN FRANKLIN DAVENPORT.

Witnesses:

R. H. EDDY, GEORGE ANDREWS. 

